The present application generally relates to pipe fittings fabricated from plastic materials, and more specifically to pipe unions fabricated from plastic materials. Polyvinyl Chloride (PVC) is the most widely used plastic piping material. However other thermoplastic materials utilized for fabricating pipe and pipe fittings, including, but not limited to, Acrylonitrile-Butadiene-Styrene (ABS), Chlorinated Polyvinyl Chloride (CPVC), Polyethylene (PE), and Cross-Linked Polyethylene (PEX). When utilized herein, the term “plastic” is to be interpreted as to including all of these materials.
Among the fittings fabricated from plastic are pipe unions. Unions are designed to allow quick and convenient disconnection of pipes for assembly, maintenance and repair. In using a pipe union to connect two pipes or fittings together, the ends of the pipe or fittings are not connected to each other, but are instead connected to a third piece, the third piece being the union. When one of the pipes or fittings needs to come apart from the other, the nut of the union is unscrewed. A union thus allows easy connection or disconnection at any time.
A union is made in three parts which shall be referred to herein as a nut, a tail piece, and a male end, where the male end may be the end of a length of pipe, a fitting, or a threaded nipple extending from a valve, pump housing, or similar equipment, which are generally referred to herein as the “end device.” The end device is connected into a piping system by attachment of male end to the tail piece by tightening of the nut. When the nut is unscrewed from the male end, the nut is free to move along a certain length of the tail piece, thereby allowing sufficient room to disconnect the end device from the piping system. When the tail piece and male end are joined, the nut provides the necessary pressure to seal the joint between the end device and the piping system.
In some cases, particularly where the end device vibrates or causes any torqueing of the male end, it is possible for the nut to work loose. For example, if the end device is a centrifugal pump with the male end on the suction side of the impeller housing, as typical for a home spa, the entire pump can be torqued by the starting and stopping of the pump motor, which can cause the nut to come loose, resulting in leakage at the union. It would therefore be desirable to have a plastic union which has integral features which prevent the nut from coming loose, even if the male end is subject to torqueing and vibration.